Angular Impact Mitigation system for bicycle helmets to reduce head acceleration and risk of traumatic brain injury

Hansen, Kirk C.; Dau, Nathan; Feist, Florian; Deck, Caroline; Willinger, Rémy; Madey, Steven M.; Bottlang, Michael

doi:10.1016/j.aap.2013.05.019

Cited by 67 publications

(66 citation statements)

References 40 publications

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“…The ability of a helmet to mitigate rotational acceleration is currently not evaluated in the standard test. This has been widely discussed, and several authors have proposed a laboratory rig to evaluate the rotational acceleration during an oblique impact and an angular moderation system in the helmet (Aare & Halldin, ; Hansen et al., ). However, in the present simulations, linear acceleration was highly correlated with rotational acceleration, suggesting that using linear acceleration as a single metric might be enough in the case of a head impact on snow.…”

Section: Discussionmentioning

confidence: 99%

Head impact in a snowboarding accident

Bailly¹,

Llari²,

Donnadieu³

et al. 2016

Scandinavian Med Sci Sports

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To effectively prevent sport traumatic brain injury (TBI), means of protection need to be designed and tested in relation to the reality of head impact. This study quantifies head impacts during a typical snowboarding accident to evaluate helmet standards. A snowboarder numerical model was proposed, validated against experimental data, and used to quantify the influence of accident conditions (speed, snow stiffness, morphology, and position) on head impacts (locations, velocities, and accelerations) and injury risk during snowboarding backward falls. Three hundred twenty-four scenarios were simulated: 70% presented a high risk of mild TBI (head peak acceleration >80 g) and 15% presented a high risk of severe TBI (head injury criterion >1000). Snow stiffness, speed, and snowboarder morphology were the main factors influencing head impact metrics. Mean normal head impact speed (28 ± 6 km/h) was higher than equivalent impact speed used in American standard helmet test (ASTM F2040), and mean tangential impact speed, not included in standard tests, was 13.8 (±7 km/h). In 97% of simulated impacts, the peak head acceleration was below 300 g, which is the pass/fail criteria used in standard tests. Results suggest that initial speed, impacted surface, and pass/fail criteria used in helmet standard performance tests do not fully reflect magnitude and variability of snowboarding backward-fall impacts.

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Section: Discussionmentioning

confidence: 99%

Head impact in a snowboarding accident

Bailly¹,

Llari²,

Donnadieu³

et al. 2016

Scandinavian Med Sci Sports

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“…The awareness of the correlation between rotational acceleration (and velocity) of the head with traumatic brain injuries encouraged further research on new protective helmet designs aiming at rotational acceleration and velocity mitigation. These efforts were focused on either improving the foam liner, for example, using highly anisotropic foam or aluminum honeycombs, or on introducing innovative designs such as adding a slip layer in the helmet structure as in case of the MIPS system…”

Section: Introductionmentioning

confidence: 99%

Optimization of Composite Foam Concept for Protective Helmets to Mitigate Rotational Acceleration of the Head in Oblique Impacts: A Parametric Study

Mosleh¹,

Pastrav

Vuure³

et al. 2017

Adv Eng Mater

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Rotational acceleration of the head is known to be the cause of traumatic brain injuries. It was hypothesized that by introducing anisotropy in a foam liner in head protection applications, for example, protective helmets, rotational acceleration transmitted to the head can be further mitigated. Therefore, composite foam with a cylinder/matrix configuration with anisotropy at "macro level" is proposed as a smart structural solution to replace single layer foam headliners of the same weight and thickness. In this paper, a parametric study on the cylinder/matrix configuration is performed and the results are compared with these of single layer expanded polystyrene foam. The structure is subsequently optimized for the best performance in mitigation of rotational acceleration and velocity. Oblique impact results show that the parameters such as the number of cylinders in a given structure, and the compliance of the matrix foam significantly affect the extent of rotational acceleration and velocity mitigation. Optimized composite foam configurations are subsequently proposed and they demonstrate a mitigation of rotational acceleration and velocity up to 44 and 19%, respectively. Moreover, relevant global head injury criteria such as HIC (Head Injury Criterion), RIC (Rotational Injury Criterion), HIP max (Head Impact Power), GAMBIT (Generalised Acceleration Model for Brain Injury Threshold), and BrIC (Brain Injury Criterion) demonstrated reduction up to 27, 67, 31, 26, and 19%, respectively.

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“…More recently, Hansen et al [27] proposed a novel Angular Impact Mitigation (AIM) system for bicycle helmets, employing an elastically suspended aluminum honeycomb liner. The impact performance under normal and oblique impacts was compared to a standard EPS helmet.…”

Section: Introductionmentioning

confidence: 99%

Helmet Design Based on the Optimization of Biocomposite Energy-Absorbing Liners under Multi-Impact Loading

et al. 2019

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Cellular materials have been used in many applications such as insulation, packaging, and protective gear. Expanded polystyrene has been widely used as energy-absorbing liner in helmets due to its excellent cost-benefit relation. This synthetic material can absorb reasonable amounts of energy via permanent deformation. However, in real-world accidents, helmets may be subjected to multi-impact scenarios. Additionally, oil-derived plastic is presently a major source of societal concern regarding pollution and waste. As a sustainable alternative, cork is a natural cellular material with great crashworthiness properties and it has the remarkable capacity to recover after compression, due to its viscoelastic behavior, which is a desired characteristic in multi-impact applications. Therefore, the main goal is to analyze the applicability of agglomerated cork as padding material in safety helmets. First, a finite element model of a motorcycle helmet available on the market was developed to assess its safety performance and to establish a direct comparison between expanded polystyrene and cork agglomerates as liners. Secondly, a new helmet model with a generic geometry was developed to assess the applicability of agglomerated cork as liner for different types of helmets, based on the head injury risk predictions by the finite element head model, YEt Another Head Model (YEAHM), developed by the authors. Several versions of helmet liners were created by varying its thickness and removing sections of material. In other words, this generic helmet was optimized by carrying out a parametric study, and by comparing its performance under double impacts. The results from these tests indicate that agglomerated cork liners are an excellent alternative to the synthetic ones. Thus, agglomerated cork can be employed in protective gear, improving its overall performance and capacity to withstand multi-impacts.

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Angular Impact Mitigation system for bicycle helmets to reduce head acceleration and risk of traumatic brain injury

Cited by 67 publications

References 40 publications

Head impact in a snowboarding accident

Head impact in a snowboarding accident

Optimization of Composite Foam Concept for Protective Helmets to Mitigate Rotational Acceleration of the Head in Oblique Impacts: A Parametric Study

Helmet Design Based on the Optimization of Biocomposite Energy-Absorbing Liners under Multi-Impact Loading

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